Is there anyone out there who really knows what happened to the Helderberg? Two inquiries have been held into the tragedy in which 159 people were killed. First came the Margo Commission, then the Truth and Reconciliation Commission. A handful of people in positions of prominence seem to know what really brought the Boeing down on that fateful night in November 1987, but as Manu reports, they've been maintaining a conspiracy of silence all this time.

• Mauritius, Mauritius, Springbok 295.

• Mauritius, Good morning.

• Good morning, we have a smoke problem and we're doing emergency descent to one-five, er, one-four-zero.

• Confirm you wish to descend to level one-four-zero.

• Ja, we have already commenced due to a smoke problem on the airplane.

• Do you request a full emergency, please, a full emergency?

• Affirmative, over, that's Charlie Charlie.

• Roger, I declare a full emergency. Roger.

Former State President PW Botha: 'Our whole country learnt with deep regret of the sad loss of one of our aircraft in the early hours this morning, near Mauritius.'

That was the face Government gave to the story, but it was the start of a gigantic conspiracy.

Since take off on that fateful evening no one, to this day, knows the full truth of the Helderberg's final hours. Flight SA 295 was en route from Taipei to Johannesburg when a fire broke out in the cargo hold.

This fire alarm was recorded by the cockpit voice recorder. Officially the fire was placed close to Mauritius. However, forensic scientist Dr David Klatzow believes there were two fires. He says the alarm was triggered by an earlier fire, only two hours into the flight.

Manu: 'Why didn't Captain Uys turn back after the first fire?'

Dr David Klatzow: 'Because he had got that first fire out and he was prepared to take that chance.'

Dr Klatzow's theory is the Helderberg was carrying volatile military cargo.

Dr Klatzow: 'Because, to have landed that aircraft with contraband cargo, a fire - and even at that stage possibly even fatalities - would have sounded the death knell for South African Airways.'

Other people confirm this belief. Brian Watkins, a retired South African Airways route manager, says it was an issue mentioned to him by a since deceased colleague.

Brian Watkins: 'He described to me the cargo as being ammunitions, weapons and explosives.'

In 1987 Johan Meyer was an avionics technician for SAA.

Johan Meyer: 'At the time of the Iran/Iraq War there was a 150mm Howitzer missile, the G5 ammunition was loaded onto aircraft that went to Amsterdam and from there to either Iran or Iraq. We weren't sure.'

Manu: 'Civilian aircraft?'

Johan: 'That's right, 747 from SAA.'

Dr Klatzow: 'It's now common knowledge that SAA was flying military cargo everywhere they wanted to go.'

Manu: 'Why not use military aircraft?'

Dr Klatzow: 'They were persona non grata in any civilised country; SAA had a limited access to these parts of the world. We know they were flying stuff back from Taiwan under the heading 'hairdryers'. We know, you just heard, SAA was flying ammunitions for the G5s all over the place. We know that pilots parked on the runways at Tel Aviv and dropped stuff that turned out to be military rockets. We know that two years ago… three years ago South African passenger aircraft were being used to ferry live hand grenades to Argentina. I mean, what does South African Airways take the flying public in this country for - a bunch of fools?'

Captain Dawie Uys had previously been forced to fly dangerous cargo from London to Johannesburg. His close friend Terry Devine confirmed this in a telephonic interview with David Klatzow. However, Terry would not speak to us on camera.

Terry Devine: 'He said he refused, and then they said, 'Well you've got to because…', you know… and then I think they contacted ZUR. And he had to fly the flight. But he then took photocopies of all the documents.'

No one knows where those copies are today, and the captain's wife, who may have them, has never granted an interview. The London - Johannesburg flight made it home, but in Taipei Captain Uys was again put under pressure.

A former Air Force pilot told David Klatzow about information that emerged on Mauritius shortly after the crash.

Former Air Force pilot: 'Dawie had had a lot of communication with people after he'd learnt what the freight was. And it was SAA, it was the Minister and the bloody works!'

Brian: 'Nine days before the crash I warned SAA about the danger of dangerous cargo.'

But his warning was ignored. Eighteen months before the crash Government had passed a law prohibiting the conveyance of dangerous cargo on passenger flights. However this legislation also empowered the Commissioner of Civil Aviation to authorise the carriage of substances like radioactive materials, flammable chemicals and military hardware … when he deemed it to be in the public interest.

Several hours before the scheduled touchdown, something went horribly wrong as flight 295 sped through the darkened skies. Those passengers would never be arriving.

At first light the search for survivors began … news of the crash was rushed around the world.

People were glued to their TV sets.

Joan Leppan: 'We never moved away from the TV. We sat at that TV all day.'

Joan Leppan lost her daughter. Heather MacNeil's name was one of the last ones to be released. Heather's son, Kiernan, was a toddler at the time of her death. Her daughter, Yolanda, was twelve at the time.

Manu: 'What do you think your Mom's thoughts would have been in those final moments?'

Joan: 'With her children I'm sure …'

13 years on and Yolanda is still searching for answers.

Yolanda: 'What it was that caused the plane to crash, and why there was a cover-up… why?'

Dr Klatzow: 'Who knows? I mean, when you look at the nonsense coming out at the Basson trial, one's not certain whether you're dealing with low-grade mental defectives, or people who, for the good of the country, were so greedy that they didn't get on with the awful things they were doing. I don't know the answer to that, but certainly the country was in the total grip of an onslaught paranoia, fuelled by the Nationalist Government of the day and enforced by their jackboot minions of the Security Police and others.'

Recorded statements indicate that this network extended into the top ranks of South African Airways. In a telephone conversation with David Klatzow, a former reservations manager divulged the secrets he was sworn to keep.

Former reservations manager: 'When I was called up there, when I was up there, I mean, my section boss phoned me and I went in and I heard them hassling and talking about chemicals; something that there were chemicals on board. These were guys I didn't know, you know, all in suits and I'd never seen them before.'

That meeting took place in this building in Braamfontein, Johannesburg. At the time of the Helderberg crash it was the national headquarters of South African Airways.

Former reservations manager: 'Just after that we were all sworn… everybody that was involved at the time, you know - we were basically told, 'You speak to nobody … ' Everything was shut up and then there was a form we had to sign.'

In Mauritius meanwhile search and rescue operations continued … back in South Africa the cover-up was gaining momentum.

At Jan Smuts Airport a crucial tape recording went missing. This tape would have revealed any communication between the Helderberg and the ZUR base station. Its disappearance left a void in the subsequent investigation. We asked former Radio Operator, Gavin Dick, what happened on that night.

Gavin Dick: 'I recall that from time to time I did try to call the Helderberg through Cellcall. There was no response coming back from them. You know, fate has its way. I never followed up to ascertain why he wasn't responding.'

Manu: 'At no time did the Helderberg try to make contact with you?'

Gavin: 'None whatsoever.'

Johan: 'That's not what he told us. The Monday after the crash, he spoke freely about it. He said they'd spoken to the Helderberg, they were some of the last people to speak to the Helderberg. He didn't stipulate at that stage, who was the other guy with him, I didn't know the other guy in ZUR station, and he said there was a fire on board just after they left Taipei.'

We went looking for the other person. Vernon Nadel, who was Gavin Dick's duty officer that night, has left SAA but he's still in the travel industry. We wanted answers from him. If Gavin didn't speak to the Helderberg that night, maybe he did.

Receptionist: 'I'm sorry he's in a very serious meeting at the moment.'

Manu: 'You can tell him people are implicating him in a cover-up.'

We left our telephone number.

Manu: 'If you have a change of mind, will you phone back? Okay, I have someone here who would like to speak to you - she has a couple of questions …'

Yolanda: 'Hello, is that Vernon?

He put the phone down.'

That was Vernon Nadel, whose offices we visited earlier today. He said he was doing me the courtesy of returning the call and was not prepared to talk. I told him people were implicating him in a cover-up and he said people could say whatever they wished, and he wasn't interested and he refused to give us an interview.

Why wouldn't Vernon Nadel talk to us about the Helderberg? And where is the missing tape now? Four years ago David Klatzow spoke to the man who'd removed it.

Dr Klatzow: 'You tell me that you signed out the tapes, that you agreed?'

Vernon Nadel: 'Yes.'

Dr Klatzow: 'You signed out the logs?'

Vernon: 'Yes.'

Dr Klatzow: 'And you gave both the tape and the log to Mickey Mitchell?'

Vernon: 'Ja.'

Why was this tape removed and passed up the chain of command? Could it be that it contained the deadly instruction to press on to Mauritius?

We offered former CEO, Gert van der Veer, a chance to explain, but he refused. Carte Blanche later established he was attending an airline safety conference in Australia.

The Margo Commission, appointed to investigate the crash, didn't seem too concerned about the disappearance of the tapes. It found there was nothing sinister, but it also never established the cause of the fire that downed the Helderberg.

Judge Margo's findings were questionable and his conduct during the inquest irregular. He summoned members of the Flight Engineers Association to his chambers as well as his home where he pressurised them to withdraw their submission of the two-fire theory.

Dr Klatzow: 'What did he say to you?'

Jimmy Mouton: 'More or less, he told us quite clearly that if our scenario happened to be proved to be true, it would mean that we would not only lose our jobs, but that SAA

would close down and it could close down the country as well because it was bigger than us and it could bankrupt the company.'

Dr Klatzow: 'What else did he say?'

Jimmy: 'Well, I don't know - that was enough to frighten all of us. When we walked out that day, when we came into the sunlight, I said to the guys, 'Don't be surprised if a PUTCO bus flattens our car and kills all four of us'. That is why we actually pulled out of it. After that I said to the guys, 'Listen, if you want to pursue this, I agree this is bigger than all of us… we're going to get burnt, we're gonna get hurt.'

Bobby Mouton: 'I always understood that it would cost the country a lot of money.'

Dr Klatzow: 'A figure of 400 million was spoken of?'

Bobby: 'Yes, that was the figure that was bandied about.'

David Klatzow interviewed both Bobby Mouton and his brother Jimmy. Jimmy later testified before the TRC.

Dr Klatzow: 'The mere fact that witnesses were summoned to a judge's house - a sitting judge in an inquiry… if it is true, is scandalous beyond measure. It's a disgrace.'

The Helderberg's Flight Engineer, Joe Bellagarda, was survived by his wife, Yvonne, and four children. Yvonne still remembers the day the Flight Engineers were forced to withdraw.

Yvonne Bellagarda: 'Every time he wanted to say something at work, I remember when it first happened, everybody used to say, 'Just keep quiet, we don't know anything for sure'.'

We wanted to hear Judge Margo's version.

Manu: 'Hi, is this Judge Margo's house?'

Voice on intercom: 'Who wants him? What's it for?'

Manu: 'My name is Manu Padayachee, and I'm from the TV programme Carte Blanche, and we're hoping that he would be able to help us.'

Voice on intercom: 'He doesn't live here anymore.'

Where does Judge Margo live? We asked a couple of neighbours who lived at number 16. They didn't know his name, but described him as a retired judge.

Calls for a new Judicial Commission to investigate the Helderberg disaster have

recently intensified. The Directorate of Public Prosecutions is investigating, but Government is yet to announce its decision.

Dr Klatzow: 'This really needs to be brought out in a proper judiciary inquiry. Civil Aviation Authorities should not be allowed to conduct this on their own.'

Manu: 'But the Margo Commission… he was a judge?'

Dr Klatzow: 'Yes?'

Manu: 'Wasn't that a judiciary commission?'

Dr Klatzow: 'So was the Harmse Commission. He was a judge, and he found there were no hit squads. If somebody ordered Uys to fly on, there is no doubt in my mind that they are guilty of murder.'

Joan: 'They should be brought to book. There's no doubt about it, you just don't do things like that.'

IMPORTANT DISCLAIMER: While every attempt has been made to ensure this transcript or summary is accurate, Carte Blanche or its agents cannot be held liable for any claims arising out of inaccuracies caused by human error or electronic fault. This transcript was typed from a transcription recording unit and not from an original script, so due to the possibility of mishearing and the difficulty, in some cases, of identifying individual speakers, errors cannot be ruled out.